Latching device for the dial on a watch movement



Jan. 13, 1970 u, GIGER ET AL LATCHING DEVICE FOR THE DIAL ON A WATCH MOVEMENT 2 Sheets-Sheet 1 Filed Dec.

Jan. 13, 1970 u. GIGER ET A-L 3,488,943

' LATGHING DEVICE FOR THE DIAL ON A WATCH MOVEMENT Filed Dec. 16, 1968 2 Sheets-Sheet 2 United States Patent 3,488,943 LATCHING DEVICE FOR THE DIAL ON A WATCH MOVEMENT Urs Giger, Solothurn, and Heinrich Stamm, Grenchen,

Switzerland, assignors t0 Eta A.G. Ehauches-Fabrik, Grenchen, Soleure, Switzerland Filed Dec. 16, 1968, Ser. No. 783,921

Claims priority, application Switzerland, Dec. 19, 1967,

17,753/67 Int. Cl. G04b 19/06 U.S. Cl. 58-127 6 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION Field of the invention This invention relates to the latching devices for the dial on a watch movement, in particular whereby the dial plate carries feet for its fixation and the movement is provided with bores adapted to the dial feet for receiving the same. The latching devices contemplated here are still more particularly of the type comprising a latch member for each dial foot, each latch member being mounted in the watch movement so as to be movable from a resting position into a working position and vice versa, each latch member further comprising a sharp edge which, in order to hold the dial in place, cooperates with a notch formed by said sharp edge in the corresponding dial foot the first time said latch member is brought in its working position after the dial has been set in place on the movement.

Description of the prior art With the known latching devices of the type indicated above, each latch member comprises a resilient split pivot fitting a bore of the base plate of the movement, said bore extending in parallel with the corresponding dial foot and being located in the vicinity of the latter. Each latch of the known devices moreover comprises an abutting surface lying on the base plate, said abutting surface being formed on a thicker latch portion, the contour of which has the shape of a spiral, this thicker portion being further bevelled so as to form a sharp cutting edge thereon. Each latch of the known devices finally comprises a head portion extending above said thicker portion and being slotted as a screw head. This slotted head enables actuating the latches of the known devices by means of a conventional screw driver.

The known latching devices have however two important drawbacks.

The first drawback of these known latching devices resides in the fact that their working position is not determined. If the dial has to be removed from the watch movement for any reason, it may occur, when it is set in place again, that the latches will be moved the second time beyond the position which they reached the first time, their sharp edges consequently cutting deeper notches in the dial feet. If the same operation has to be repeated sometimes, it may occur that the sharp edges of the latches either cut the dial feet throughout or permit the latches to be rotated without reaching a working position in which they would be locked in a precise angular position.

The second drawback of the known latching devices resides in the rather uneasy mode of actuation of the latch members. After the dial has been set in place on the watch movement, the latter has to be turned up for actuating the latch members. During that motion either one of the dial feet can move relative to the watch movement so that after having actuated the latch members, the dial does not correctly lie on the movement.

There are actually latching devices known in the art by means of which the abovementioned drawbacks can be removed. Instead of latch members extending in parallel with the dial feet, these known latching devices comprise latch members which are perpendicular to the dial feet, said latch members consisting of screws inserted in bores provided in the side face of the watch movement base plate.

In calendar watches in which the dial feet are often located in the immediate vicinity of the base plate outer edge, these last known devices have in turn the drawback that their locking screws have to be located in base plate bores which are provided in a substantially tangential direction. Actuating such latch members is obviously very uneasy and can hardly be effected by automatic means.

The problem which had to be solved thus consisted in the provision of a latching device for the dial feet which could be actuated as easily as safely even by automatic means which do not require any delicate adjusting operation.

SUMMARY OF THE INVENTION This problem is solved according to the invention by means of a latching device of the type indicated hereabove wherein each latch member is formed with an actuating portion accessible from outside the movement and moving substantially along a radial line thereof inwards when the latch member moves itself from its resting position toward its working position, these latch members thus simply requiring a mere pushing action exerted on their actuating portion for causing the latch member to move from its resting position into its working position.

According to a particular object of the invention a substantial simplification can be achieved in particular when the dial has to be set in place by automatic or at least half automatic means. For that purpose, the actuating portion of each latch member has only to be arranged, on the one hand, so as to protrude laterally from the movement when the latch member is in its resting position, and, on the other hand, so as to be flush with the side face of the movement when said latch member is in its working position.

In this particular embodiment the actuating portion of each latch member can be brought in working position by merely pushing the same by means of a rod substan tially extending along a radial line of the watch movement and having a cross-section substantially exceeding that of the actuating portion of the latch members. In that event it obviously appears that neither the position of the rod used for actuating the latch members nor the stroke of that rod have to be adjusted with a great precision. If said rod were indeed not perfectly alined with the actuating portion of the latch member, it will still catch the same, because of its larger cross-section. As regards the stroke of said rod, it is automatically limited by the edge of the watch movement against which the end face of the rod will butt when the latch has reached its working position.

In order that the sharp edge of the latch members of the latching device improved according to the invention do not cut a notch deeper and deeper in the corresponding dial foot if the dial has to be removed from the watch movement and set in place again many times, a still further particular object of the invention consists in using a latch member comprising, on the one hand, a rigid body portion cooperating with corresponding guiding means provided on the watch movement and, on the other hand, a resilient arm connected to said rigid body portion, the sharp edge of the latch member being provided on said resilient arm and extending along the same.

BRIEF DESCRIPTION OF THE DRAWING Two embodiments of the latching device improved according to the invention are represented diagrammatically and by way of example in the accompanying drawing in which:

FIG. 1 is a plan view of the first embodiment, the latch member being in its resting position;

FIG. 2 is a similar plan view of the same embodiment, the latch member being in its working position;

FIG. 3 is a cross-section along line III-III of FIG. 2, and

FIG. 4 is a plan view similar to FIG. 2 showing the second embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawing only one dial foot 1 has been represented together with the corresponding members of the improved latching device. Foot 1 extends within a bore 2 of the base plate 3 of the watch movement.

This bore extends under the bevelled outer part 4 of the balance cock 5, a part of which has been broken away in the drawing. The surface of base plate 3, which is directed toward cock 5, is provided with a recess 6 having the shape of the upper portion of a heart. A groove 7 is moreover cut in the side wall of the right auricle of recess 6 in the ground portion of said side wall. Groove 7 intersects bore 2 of the dial foot 1. A stud 8 and a stop 9 protrude from the bottom of recess 6. A latch 10 provided for cooperation with foot 1 is mounted on pivot 8 so as to be rockable thereabout. A cut-out corresponding to pivot 8 is therefore provided in a rigid portion 10a of latch 10. In order that latch 10 snugly encompasses stud 8 its rigid body portion 10a is provided with a slot 11. Latch 10 moreover comprises an arm 10b which is yieldably connected to body portion 10a by means of an arcuate lever portion 10c. The edge 12 of arm 10b, which is opposed to stud 8, is bevelled so as to form a sharp cutting edge 13. In a plan view this cutting edge has the shape of an arc of a circle, the center of which is however off-set with respect to stud 8 so that the outer end of edge 13 will be farther away from stud 8 than the inner end of edge 13. Arm 10b of the latch member partly extends within groove 7 which thus holds the latch member on the bottom of recess 6. For that purpose the width of groove 7 corresponds to the thickness of latch member 10.

When this latch member 10 is in its resting position represented in FIG. 1, it lies against stop 9. In that position bore 2 is free so that foot 1 of the dial can be introduced therein without any ditficulty. The outer end of arm 10b protrudes laterally from base plate 3 of the watch movement. Since latch 10 is snugly fitted on stud 8, it remains in its resting position even if the watch movement is turned over for setting the dial 18 (FIG. 3) in place.

Once the dial 18 has been set on the watch movement in such manner that its feet extend within the corresponding movement bores and stand in the desired axial position, it can be locked in place by merely pushing the latch members 10 by means of a rod 14 (FIG. 2) until this rod 14 butts against the side edge of base plate 3.

During the motion which the latch members 10 carry out under the control of rods 14, they come once in contact with the corresponding foot 1 at some predetermined point of their sharp edge 13. It appears that that point of edge 13 is located in the vicinity of its inner end, i.e. on

a portion of arm 1% which is connected to the rigid body portion 10a of the latch in a still relatively rigid manner. Upon moving further on the latch 10 causes its sharp edge 13 to cut a notch in foot 1. The more latch 10 is pushed into the movement, the deeper edge 13 cuts in foot 1, because of the excentricity of edge 13. Since this edge 13 is provided on a resilient arm of the latch memher, it stops however cutting the dial foot before the latch 10 has reached its working position, namely when the resistance of foot 1 balances the bending resistance of the arcuate lever portion of the latch. During the last phase of the displacement of latch 10' its edge 13 merely slides in the notch which has just been provided in foot 1, thus causing a progressive bending of the arcuate lever portion 100 of the latch. In the working position represented in FIG. 2 latch 10 is accordingly not only locked by the frictional engagement of latch 10 on stud 8, but also by the frictional engagement produced by the arcuate lever portion 100 between edge 13 and the dial foot.

Recess 6 is substantially covered by the outer edge 4 of balance cock 5. A small lunulate cut-out 15 provided in the balance cock, however, provides for a free access to latch 10 thus enabling unlatching foot 1 and removing dial 18. For this purpose the latch member comprises a projection 16 provided at the outer end of its arm 10b so that it may be caught by means of the end 17 of a screw driver extending through cut-out 15 of the balance cock thereby enabling latch 10 to be removed from its working position and to be restored in its resting position represented in FIG. 1. For actuating latch 10 in that way the screw driver 17 can rest on stop 9 as indicated in FIG. 2.

In order to lock the second dial foot (not shown), a second latch identical to that described is provided at the appropriate place of base plate 3. The recess which has to be provided in that base plate for the second latch can be covered, according to the arrangement of the bridges on the base plate, by the outer edge either of a wheel bridge or of the barrel bridge in the same manner as recess 6 is covered by the outer edge of the balance cock.

The disclosed latching device obviously enables setting dial 18 on the watch movement and fixing the same thereon by automatic means. When rod 14 belongs to such an automatic device, adjusting the same does not raise any difficulty. The cross-section of rod 14 is substantially larger than that of arm 10b of the latch member so that rod 14 need only be coarsely alined with that arm of the latch member. Moreover, the stroke of rod 14 is automatically limited by the edge of base plate 3, because in the working position of latch 10, the outer end of arm 10b is flush with the base plate edge as shown in FIG. 2.

If it would happen once that the latch member, contrary to all expectations, would no longer be locked in its working position represented in FIG. 2 in a sufficiently strong manner, for instance after having removed the dial and set it in place again a very great number of times, the sizes of recess 6 as well as of groove 7 are chosen in such manner that the latch 10 can be pushed into the movement beyond the position represented in FIG. 2 thus bending the arcuate lever portion 10 of the latch even more and setting the latter in a position which it will not leave incidentally.

In the second embodiment the latch member associated with dial foot 1 is no longer arranged as a rocking lever, but as a slide. For receiving this slide an elongated radial recess 19 is provided in base plate 3. Grooves 19a, 19b are provided in the parallel side walls of this recess in the ground portions thereof, the width of these grooves corresponding to the thickness of slide 20. Slide 20 comprises a rigid body portion 201; which partly extends within groove 19a serving as guiding means for the slide. An arm 20b yieldably connected to the rigid body portion 20a is provided with a sharp edge 21 as in the first embodiment. The shape of edge 21 is chosen so that it cooperates with foot 1 in the same manner as edge 13 in the first embodiment, when slide 20 is pushed inwards. A pin 22 projecting from the bottom of recess 19 prevents slide 20 from falling out of the movement and serves at the same time as a stop for determining the position of rest of slide 20.

In order to unlock foot 1, slide 20 can be pulled from its working position represented in FIG. 4 and moved in its position of rest by means of a screw driver 17 as in the first embodiment. For this purpose a lunulate cut-out 23 is provided in the bevelled outer edge 4 of the balance cock 5 which covers recess 19. In this embodiment the second dial foot (not shown) can be locked in the corresponding base plate bore by means of a second slide identical to the first one.

In order to lock the dial on the watch movement, the two slides of the second embodiment can obviously be actuated under the same conditions as the rocking levers of the first embodiment.

We claim:

1. In a watch having a dial plate carrying feet for its fixation and a movement provided with bores adapted to the dial feet for receiving the same, a latching device comprising, for each dial foot, a latch member mounted in the watch movement so as to be movable from a resting position into a working position and vice versa, said latch member comprising a sharp edge and being formed with an actuating portion accessible from outside the movement and moving substantially along a radial line of the movement inwards when said latch member moves itself from its resting position toward its working position, each dial foot being provided with a notch formed by said sharp edge of the corresponding latch member the first time said latch member is brought in its working position after the dial has been set in place on the movement, said sharp edge and said notch of each corresponding pair of latch member and dial foot cooperating with each other and locking said dial on said movement when the latch members associated with the dial feet are in their working positions.

2. The latching device as claimed in claim 1, wherein said actuating portion of each latch member protrudes laterally from the movement when the latch member is in its resting position and is flush with the side face of the movement when said latch member is in its working position.

3. The latching device as claimed in claim 1, further comprising guiding means on the watch movement for each latch member, each latch member comprising a rigid body portion cooperating with the corresponding guiding means and a resilient arm connected to said rigid body portion, said sharp edge being provided on said resilient arm and extending along the same.

4. The latching device as claimed in claim 3, wherein the distance of the different points of said sharp edge to said guiding means and the flexibility of said resilient arm of the latch both increase in proportion to the distance from the inner end of said sharp edge to the outer end thereof. I

5. The latching device as claimed in claim 4, wherein each latch member is arranged as a lever whereby its rigid body portion is pivotally mounted on a fixed stud constituting said guiding means, and its resilient arm, constituting said actuating portion, is connected to said rigid body portion by means of an arcuate lever portion.

6. The latching device as claimed in claim 4, wherein each latch member is arranged as a split slide having one leg constituting said rigid body portion and being inserted in a groove provided on the base plate of the watch movement and constituting said guiding means, while the other leg is resilient and carries said sharp edge.

References Cited UNITED STATES PATENTS 523,913 7/1894 Hunter 58127 598,523 2/1898 Linovall 58-127 613,556 11/1898 Brown 58-127 1,074,130 9/1913 Miller 58-127 FOREIGN PATENTS 53,806 11/ 1911 Switzerland. 82,809 10/ 1919 Switzerland. 120,846 6/ 1927 Switzerland.

RICHARD B. WILKINSON, Primary Examiner STANLEY A. WAL, Assistant Examiner 

